这里是一个使用Python解决该问题的示例代码：

import os

def count_lines(file_path):
    with open(file_path, 'r') as file:
        lines = file.readlines()
    return len(lines)

def copy_file(file_path, new_file_name):
    with open(file_path, 'r') as file:
        lines = file.readlines()
    if len(lines) < 500:
        with open(new_file_name, 'w') as new_file:
            new_file.writelines(lines)

def traverse_directory(directory_path):
    for root, dirs, files in os.walk(directory_path):
        for file_name in files:
            file_path = os.path.join(root, file_name)
            line_count = count_lines(file_path)
            if line_count < 500:
                new_file_name = f"new_{file_name}"
                copy_file(file_path, new_file_name)

# 使用示例
directory_path = '/path/to/directory'  # 替换为实际的目录路径
traverse_directory(directory_path)

以上代码中，count_lines函数用于计算文件的行数，copy_file函数用于复制文件到新的文件名，traverse_directory函数用于遍历目录中的文件并执行计算和复制操作。

你需要将directory_path变量替换为实际的目录路径，然后运行traverse_directory(directory_path)来执行遍历和计算复制操作。